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Table 1 Characteristics of patients with recurrent metastatic breast cancer by age (years) at diagnosis from a breast cancer cohort in China between 1989 and 2020

From: Association between age at initial diagnosis and post-metastasis mortality among women with recurrent metastatic breast cancer in China

Characteristics All
(n= 1,636)
< 40
(n= 363)
40–64
(n= 1,173)
≥ 65
(n= 100)
P
Year at diagnosis      0.099
 1989–2007 490 (29.95) 98 (27) 354 (30.18) 38 (38.00)  
 2008–2020 1,146 (70.05) 265 (73) 819 (69.82) 62 (62.00)  
Ethnic group      0.799
 Minority 28 (1.71) 6 (1.65) 20 (1.71) 2 (2.00)  
 Han 1,472 (89.98) 322 (88.71) 1,058 (90.2) 92 (92.00)  
 Unknown 136 (8.31) 35 (9.64) 95 (8.1) 6 (6.00)  
Insurance type      0.004
 Urban schemes 1,159 (70.84) 249 (68.6) 823 (70.16) 87 (87.00)  
 Rural schemes 462 (28.24) 112 (30.85) 337 (28.73) 13 (13.00)  
 Unknown 15 (0.92) 2 (0.55) 13 (1.11) 0  
Education (years)      < 0.001
 ≤ 6 241 (14.73) 23 (6.34) 200 (17.05) 18 (18.00)  
 7–9 485 (29.65) 106 (29.2) 364 (31.03) 15 (15.00)  
 10–12 293 (17.91) 66 (18.18) 205 (17.48) 22 (22.00)  
 > 12 250 (15.28) 95 (26.17) 141 (12.02) 14 (14.00)  
 Unknown 367 (22.43) 73 (20.11) 263 (22.42) 31 (31.00)  
Marital status      < 0.001
 Non-married 23 (1.41) 15 (4.13) 8 (0.68) 0  
 Married 1,487 (90.89) 315 (86.78) 1,078 (91.9) 94 (94.00)  
 Unknown 126 (7.7) 33 (9.09) 87 (7.42) 6 (6.00)  
BMI (kg/m2)      < 0.001
 < 23 616 (37.65) 175 (48.21) 409 (34.87) 32 (32.00)  
 ≥ 23 654 (39.98) 117 (32.23) 500 (42.63) 37 (37.00)  
 Unknown 366 (22.37) 71 (19.56) 264 (22.51) 31 (31.00)  
Menopausal status      < 0.001
 Premenopausal 918 (56.11) 345 (95.04) 572 (48.76) 1 (1.00)  
 Postmenopausal 713 (43.58) 16 (4.41) 599 (51.07) 98 (98.00)  
 Unknown 5 (0.31) 2 (0.55) 2 (0.17) 1 (1.00)  
Comorbidity      0.016
 No 1,435 (87.71) 332 (91.46) 1,021 (87.04) 82 (82.00)  
 Yes 201 (12.29) 31 (8.54) 152 (12.96) 18 (18.00)  
Hormone receptor status      0.232
 Negative 525 (32.09) 103 (28.37) 391 (33.33) 31 (31.00)  
 Positive 1,015 (62.04) 242 (66.67) 708 (60.36) 65 (65.00)  
 Unknown 96 (5.87) 18 (4.96) 74 (6.31) 4 (4.00)  
HER2 status      < 0.001
 Negative 949 (58.01) 243 (66.94) 640 (54.56) 66 (66.00)  
 Positive 398 (24.33) 67 (18.46) 312 (26.6) 19 (19.00)  
 Unknown 289 (17.67) 53 (14.6) 221 (18.84) 15 (15.00)  
Ki-67 level      < 0.001
 < 14% 222 (13.57) 37 (10.19) 155 (13.21) 30 (30.00)  
 ≥ 14% 1,129 (69.01) 262 (72.18) 812 (69.22) 55 (55.00)  
 Unknown 285 (17.42) 64 (17.63) 206 (17.56) 15 (15.00)  
Molecular subtype      0.001
 Luminal A 160 (9.78) 41 (11.29) 99 (8.44) 20 (20.00)  
 Luminal B 714 (43.64) 173 (47.66) 502 (42.8) 39 (39.00)  
 HER2-positive 187 (11.43) 28 (7.71) 150 (12.79) 9 (9.00)  
 Triple-negative 289 (17.67) 65 (17.91) 205 (17.48) 19 (19.00)  
 Unknown 286 (17.48) 56 (15.43) 217 (18.5) 13 (13.00)  
Tumor sizea      0.078
 T1 295 (18.03) 62 (17.08) 206 (17.56) 27 (27.00)  
 T2 759 (46.39) 161 (44.35) 549 (46.8) 49 (49.00)  
 T3 161 (9.84) 43 (11.85) 113 (9.63) 5 (5.00)  
 T4 199 (12.16) 40 (11.02) 147 (12.53) 12 (12.00)  
 Unknown 222 (13.57) 57 (15.7) 158 (13.47) 7 (7.00)  
Nodal statusa      0.734
 N0 417 (25.49) 98 (27) 287 (24.47) 32 (32.00)  
 N1 439 (26.83) 102 (28.1) 313 (26.68) 24 (24.00)  
 N2 273 (16.69) 59 (16.25) 199 (16.97) 15 (15.00)  
 N3 386 (23.59) 77 (21.21) 285 (24.3) 24 (24.00)  
 Unknown 121 (7.4) 27 (7.44) 89 (7.59) 5 (5.00)  
Metastatic sites
 Bone      0.117
  No 1,101 (67.30) 244 (67.22) 799 (68.12) 58 (58.00)  
  Yes 535 (32.70) 119 (32.78) 374 (31.88) 42 (42.00)  
 Brain      0.124
  No 1,431 (87.47) 317 (87.33) 1,020 (86.96) 94 (94.00)  
  Yes 205 (12.53) 46 (12.67) 153 (13.04) 6 (6.00)  
 Viscera      0.060
  No 701 (42.85) 140 (38.57) 510 (43.48) 51 (51.00)  
  Yes 935 (57.15) 223 (61.43) 663 (56.52) 49 (49.00)  
 Contralateral breast      0.065
  No 1,503 (91.87) 323 (88.98) 1,086 (92.58) 94 (94.00)  
  Yes 133 (8.13) 40 (11.02) 87 (7.42) 6 (6.00)  
 Others      0.089
  No 1,318 (80.56) 291 (80.17) 938 (79.97) 89 (89.00)  
  Yes 318 (19.44) 72 (19.83) 235 (20.03) 11 (11.00)  
 Local recurrence      0.622
  No 1,178 (72.00) 258 (71.07) 844 (71.95) 76 (76.00)  
  Yes 458 (28.00) 105 (28.93) 329 (28.05) 24 (24.00)  
Histological type      0.071
 Ductal 1,368 (83.62) 304 (83.75) 975 (83.12) 89 (89.00)  
 Others 132 (8.07) 34 (9.37) 89 (7.59) 9 (9.00)  
 Unknown 136 (8.31) 25 (6.89) 109 (9.29) 2 (2.00)  
Histological grade      0.265
 I/II 318 (19.44) 65 (17.91) 226 (19.27) 27 (27.00)  
 III 685 (41.87) 161 (44.35) 484 (41.26) 40 (40.00)  
 Unknown 633 (38.69) 137 (37.74) 463 (39.47) 33 (33.00)  
Surgery      0.767
 No 63 (3.85) 16 (4.41) 44 (3.75) 3 (3.00)  
 Yes 1,573 (96.15) 347 (95.59) 1,129 (96.25) 97 (97.00)  
Anyradiotherapy      0.002
 No 807 (49.33) 158 (43.53) 586 (49.96) 63 (63.00)  
 Yes 829 (50.67) 205 (56.47) 587 (50.04) 37 (37.00)  
Any chemotherapy      0.006
 No 242 (14.79) 41 (11.29) 177 (15.09) 24 (24.00)  
 Yes 1,394 (85.21) 322 (88.71) 996 (84.91) 76 (76.00)  
Any hormonal therapy      0.012
 No 605 (36.98) 114 (31.4) 460 (39.22) 31 (31.00)  
 Yes 1,031 (63.02) 249 (68.6) 713 (60.78) 69 (69.00)  
Any targeted therapy      0.096
 No 1,431 (87.47) 309 (85.12) 1,029 (87.72) 93 (93.00)  
 Yes 205 (12.53) 54 (14.88) 144 (12.28) 7 (7.00)  
  1. BMI was classified into < 23 kg/m2 (non-overweight) and ≥ 23 kg/m2 (overweight) according to the recommendation to Asian populations
  2. aInitial primary breast tumor
  3. HER2 human epidermal growth factor receptor 2, BMI Body mass index